As a method for peeling off asphalt pavement during a repair work of an asphalt-paved road, or the like, there have been known a manual chipping technique and a water-jet technique.
However, in cases where the chipping technique is applied to an asphalt pavement which is paved, for example, on a steel plate deck of a bridge or the like, the steel plate deck is liable to be scratched, and large vibration and noise are generated. Moreover, operation efficiency is extremely low. Thus, the application is limited to a small-scale repair work.
In cases where the water-jet technique is applied thereto, high-pressure water is jetted to a position around a boundary between the asphalt pavement and the steel plate deck to peel off the asphalt pavement, and thereby a bonding layer on an upper surface of the steel plate deck can also be removed. However, large vibration and noise are generated as with the chipping technique. Moreover, a large volume of water is used therein, which leads to a need for large-scale water-supply and wastewater-treatment equipment.
With a view to solving the above problems, it has been proposed a peeling technique, as disclosed in the following Patent Document 1. As shown in FIG. 13, in this technique, microwave generated from a microwave generator 200 is emitted from a microwave irradiator 202 to an asphalt road surface 204 to heat up and soften an asphalt layer 206. Then, the softened asphalt layer 206 is cut and peeled off using a push-cutting blade 208. This makes it possible to peel off the asphalt layer 206 without generating large vibration and noise.
However, the technique disclosed in the Patent Document 1 is designed to heat up and soften the entire asphalt layer 206, which leads to a need for a large amount of electric power. Moreover, the entirely softened asphalt layer 206 is hard to handle during removal thereof, and difficult to perform a loading operation. Moreover, during the loading operation, an additional operation, such as a cleanup operation, is required due to spilling and scattering of aggregates, sand and others in the asphalt layer 206.
As shown in FIG. 14, a hot peeling apparatus 210 disclosed in the following Patent Document 2 is designed to generate an alternating magnetic field from an electromagnetic induction coil 212 supplied with a high-frequency electric power, in such a manner that an eddy current is produced in a surface of a metal plate 214 to cause self-heating of the metal plate 214, so as to allow a film 216 on the metal plate 214 to be heated and peeled off.
However, a layer having a thickness of about 0.1 to 5.0 mm, such as the film 216, is warped upwardly and naturally peeled off by heating, whereas a thick layer, such as an asphalt pavement, is hardly peeled off only by heating. Even if an asphalt pavement is entirely softened by supplying a large amount of high-frequency electric power to the electromagnetic induction coil 212, the asphalt pavement after being peeled off is hard to handle as with the Patent Document 1, and the metal plate 214 is likely to be excessively heated to cause thermal degradation.
As shown in FIG. 15, in an induction heating apparatus 230 disclosed in the following Patent Document 3, when an alternating current is supplied to an electromagnetic induction coil 222 provided inside a manhole frame 220, an alternating magnetic flux is generated to pass through the inside of the manhole frame 220 via a flange 224 serving as a flux path member. An induction current generated by the alternating magnetic flux flows along the manhole frame 220, and thereby the manhole frame 220 is heated by Joule heat. Then, gussasphalt 228 is fluidized by the heat, so that a gap formed between an outer peripheral surface of the manhole frame 220 and an existing pavement 226 is filled with the gussasphalt 228.
However, even if the thermally fluidizable gussasphalt 228 is used as an asphalt pavement, and the asphalt pavement is entirely softened by heating using the hot peeling apparatus 210 as disclosed in the Patent Document 2, the asphalt pavement after being peeled off is hard to handle as with the Patent Document 1.                [Patent Document 1] JP 2000-303408A        [Patent Document 2] JP 04-267091A        [Patent Document 3] JP 01-198905A        